Method of supplying sand to blow head of blow molding machine

Abstract

Before supplying molding sand into the blow head, a blow-in port of the mold-defining device is connected to a blow-off port of the blow head so that molding sand flowing out of the blow-off port is received by the device after the molding sand has been supplied to the blow head. Preferably, after molding sand has been charged into the mold space but before the mold-defining device is moved out of engagement with the blow head, sand remaining in the blow-off port is hardened.

We claim: 
     
       1. A method of supplying molding sand to a blow head having blow-off ports, so that the molding sand can later be blown from the blow head through the blow-off ports into a device that defines a mold space, through at least one blow-in port of the device, wherein the device comprises a substantially straight member rotatably supported on a rotatable mount, the member has a first flask at one end thereof and a second flask at the other end thereof, the first flask and the second flask are configured to engage each other to define the mold space, and each of the first flask and the second flask has a blow-in port at one side thereof, said method comprising the steps of: placing the blow head in a predetermined position when the blow head is empty and has not been fed with the molding sand;   disposing the member in a vertical position at one side of the blow head;   engaging the first flask with the second flask, thereby defining the mold space so that said mold space communicates with each said blow-in port;   rotating the member through ninety degrees in a horizontal plane, thereby engaging each said blow-in port with a different one of the blow-off ports; and   after the engagement, introducing a predetermined amount of the molding sand into the blow head.   
     
     
       2. A method of producing a mold by blowing molding sand from a blow head into a device that defines a mold space, through blow-off ports of the blow head and at least one blow-in port of the device, wherein the device comprises a substantially straight member rotatably supported on a rotatable mount, the member having a first flask at one end thereof and a second flask at the other end thereof, the first flask and the second flask are configured to engage each other to define the mold space, and each of the first flask and the second flask has a blow-in port at one side thereof, said method comprising the steps of: (a) placing the blow head in a predetermined position when the blow head is empty and has not been fed with the molding sand;   (b) disposing the member in a vertical position at one side of the blow head;   (c) engaging the first flask with the second flask, thereby defining the mold space so that said mold space communicates with each said blow-in port;   (d) rotating the member through ninety degrees in a horizontal plane, thereby engaging each said blow-in port with a different one of the blow-off ports;   (e) after step (d), introducing a predetermined amount of the molding sand into the blow head, the predetermined amount at least substantially equaling an amount that fills the mold space and the blow-off ports;   (f) after step (e), introducing compressed air into the blow head, thereby charging the predetermined amount of the molding sand into the mold space and the blow-off ports;   (g) after step (f), hardening the molding sand in the blow-off ports so that the molding sand in the blow-off ports does not drop freely; and   (h) after step (g), moving the member out of engagement with the blow head.